What causes depression?

Research suggests that depression may result from four factors: biochemical, genetic, environmental and psychological.

Scientists have not discovered a "depression gene" but they have seen evidence, based on family histories, that suggests there may be a genetic link. Children of parents with major depression have a greater chance of experiencing depression than the general population. But depression also occurs in individuals in families without a history of the illness, so researchers continue to study additional factors.

People with depression have abnormal levels of brain chemicals called neurotransmitters, the messengers between the brain and the body.

People with certain characteristics such as low self-esteem and pessimism also tend to be more prone to develop depression. These characteristics, combined with stressors such as illness, relationships, major life events and financial problems can contribute to patterns of depressive illness. The onset of depression frequently is a combination of these causes.

Depression can be hereditary and hormone shifts and changes can definitely trigger it or worsen it. There are many medications available to help you. You may want to ask your doctor about a birth control pill, as sometimes that can help even out hormonal fluctuations. There are many antidepressants that can help stabilize your mood. Getting exercise is great stress reliever and can help with depression as well. Lastly, you may want to try talk therapy - a therapist, either a social worker or psychiatrist, may be able to provide you with techniques to help you manage your feelings of frustration and mood swings. Your doctors can work with you to choose the best treatment for you and perhaps they can recommend some therapists in your area.

Depression is caused by many factors, from the psychological, social, and environmental to the genetic, and metabolic. While it seems all depression are the same, perhaps caused by a serotonin deficiency, and require treatment with medication; in fact, depression is not ONE illness. It is very important to know the causes of depression and get proper treatment.

Genetics: There is growing evidence that there may be certain genetic vulnerabilities for depression.

Psychology and social factors: Helplessness, particularly around core issues (the need to be loved, to be loving, to have a sense of power, success, or control) reduces one’s self esteem.

Nutrition: Deficiencies, due to poor diet, poor digestion, absorption, or increased need for vitamins and minerals. Fat soluble vitamins (Vitamin D, Coenzyme Q 10) can cause or contribute to depression and have been shown to prevent antidepressant response.

Digestive disorders: Celiac disease and irritable bowel are associated with depression, quite possibly because they reduce availability of nutrients. Bacterial overgrowth of the small intestine can, as an example, reduce absorption of B12, leading to depression.

Immune system: Infection or inflammatory condition can precipitate, cause, worsen, or prevent response to standard treatment for depression.

Drugs and detoxification: Numerous drugs can cause depression, including a variety of medications for heart disease, antacids, antibiotics, anti-seizure medications, benzodiazepines, pain medications, hormones, asthma medications, over-the-counter medications.

Mitochondrial dysfunction: Can lead to marked reductions in energy, resulting in what appears to be depression.

Hormonal problems: Any hormonal system, when not functioning properly, can cause a mood disorder.

Tumors: Brain tumors often present with a psychiatric manifestation such as depression.

Sleep disorders: sleep apnea, nocturnal myoclonus, restless legs, decreased REM latency are all associated with depression.

Cardiovascular disease: reductions in cardiovascular function, oxygenation of the brain, exercise capacity, blood flow to the brain are all associated with depression, and can contribute to or cause depression.

Miscellaneous: anemia, B12 deficiency, bleeding, severe lung disease leading to decreased oxygenation of the brain, obesity, Wilson’s disease, and electrolyte abnormalities.

There are many causes for depression, each reflecting different influences, yet most of these causes fall into two categories: organic or situational. Organic factors typically reflect biological vulnerabilities, such as family history of depression, while situational factors are most associated with life events, such as loss of a loved one due to death or divorce.

Depression can be brought on by a number of experiences from experiencing a death or loss, to unexpressed anger, inward aggression, negative emotional behavior, drug abuse, and biochemical imbalances brought on by amino acid and other nutrient deficiencies.

Other triggers of depression may include: tension, stress, fear, chemical imbalances in your brain, thyroid disorders, food allergies, nutritional deficiencies, sugar consumption, poor diet and lack of exercise.

Your modern lifestyle plays a key role in depression. Many of you are overly stressed, overworked, lacking exercise, amped up on stimulants, and consuming way too many processed foods that lack nutrients.

Depression is a multi-factorial issue. While conventional medicine focuses only on neurotransmitters, naturopathic and holistic medicines are at an advantage to treat the many factors that contribute to depression:

• sleep and lifestyle issues
• lack of exercise
• poor diet choices and poor digestion
• inflammation in the body and the brain
• hormonal imbalances
• stress and spiritual issues
• nutrient and healthy oil deficiencies
• environmental toxicity

Decades of strict research have confirmed that depression results from a chemical imbalance in the brain. Often, this imbalance can be treated and rectified. It has nothing to do with character weakness or inability to cope.

The brain's chemicals become imbalanced for a number of reasons. Some individuals are genetically predisposed to depressive illness. Just as a diabetic's body does not make enough insulin, the bodies and brains of some depressed people do not create an ideal balance of neurotransmitters. In many cases, serious illness such as heart disease, diabetes or cancer sends some into depression. Beyond the fear and stress these diseases can cause, the very medications that treat them can initiate, mimic or intensify depression.

Events can send individuals into depression as well. When someone loses a loved one, of course mood will plummet. If the brain cannot revive from this lower mood on its own, medication and/or therapy often does the trick, returning the neurotransmitters to optimal levels. After a significant period, the individual can withdraw from the medication to monitor whether the better mood can be sustained. Many people need only be on antidepressant medication for a year or less.

The brain is a complex collection of cells comprised of a left and right hemisphere. These hemispheres consist of four lobes: the parietal lobe, the occipital lobe, the frontal lobe, and the temporal lobe. Each lobe serves a different role and carries out a multitude functions as each one is genetically designed to control a different aspect of the essential bodily functions. The frontal lobe controls the ability of a person to plan, reason, solve problems, control emotions and even regulates parts of speech. The parietal lobe is associated with movement and regulates recollection, direction, and stimuli. The occipital lobe, being in the back of the brain, controls all functions associated with visual abilities. Lastly, the temporal lobe is associated with several different functions such as hearing abilities, memory, and verbal communication. Due to the important role that each lobe serves, an inconsistency in any one of them could prove to be detrimental. For example, a discrepancy in the functions of the temporal lobe can lead to irregularities in an individual’s behavior and mood.

Furthermore, the temporal lobe plays another explicit role in depression, as it contains within its region the hippocampus, which is a mass of neurons that plays several roles. According to Fritchsy et al. (1998), 90% of the neurons in the hippocampus are the glutamatergic pyramidal and granule cells, and 10% are  γ-aminobutyric acid (GABA)-producing interneurons. One of the primary functions of the hippocampus is the ability to control long-term memories as they relate to personal events and emotions (Eichenbaum, H. (2004). According to a research study performed by Posener et al. (2003), which utilized magnetic resonance imaging to take pictures of the hippocampus of 27 individuals with depression and 42 individuals with no symptoms of depression, the structural shape of the hippocampus of an individual with depression is abnormal. A normal hippocampus is shaped like a seahorse and an abnormal one becomes round. Thus, any notable structural discrepancy in the shape of the hippocampus found in the cerebral cortex can lead an incongruity in its functions, thus contributing to the discrepancy in the body’s equilibrium, as evidenced by the study performed by Posener et al. (2003) on the hippocampus. 

Sometimes depression is stress-induced and caused by a clear trigger. It may be a painful divorce, a death in the family, or, for military personnel, time in combat. If the stressor is reduced or removed, depression may or may not be lifted. According to Alan J. Gelenberg, MD, professor and chair of psychiatry at Penn State's Milton S. Hershey Medical Center, physical illness can cause depression. Most doctors will do a physical exam. If your doctor thinks a thyroid problem, substance abuse, or other health condition is the cause of your depression, lab tests may be in order. Some medications can also cause symptoms of depression.

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Depression can be the result of psychological or physiological factors. The most significant psychological theory is the "learned helplessness" model, which theorizes that depression is the result of habitual feelings of pessimism and hopelessness. The chief physiological theory is the "monoamine hypothesis," which stresses imbalances of monoamine neurotransmitters, such as serotonin, epinephrine, and norepinephrine. Serotonin deficiency is the most common biochemical cause.

It is important to rule out simple organic factors that are known to contribute to depression, such as nutrient deficiency; drug use, including of many prescription and illicit drugs; consumption of alcohol, caffeine, and nicotine; hypoglycemia; hypothyroidism; and food allergy.

Depression can be caused by many factors. Most of the time, it’s a reaction to stressful life experiences, such as the loss of a loved one to death or divorce, the loss of a job, ongoing and severe familial stresses, and so forth. In addition to normal life stresses, certain biological changes can also trigger depression. These include a number of physical diseases. Some medical conditions change body chemistry and ultimately affect the delicate chemical balance of the brain. For this reason, it is strongly recommended that you see your physician and have a complete physical exam and basic lab tests to determine whether there are any medical conditions present that may be causing your depression.

Historically, theories have varied about whether depression and other upsetting emotional states are biologically based or primarily caused by external events. In any case, how we respond to traumatic events in our lives is understandably influenced by past experiences, both good and bad.

The vast expansion of the mental health system, the rise of neuroscience, the profit-making motive of pharmaceutical companies, and the preference of health insurers for the quick fix of drugs over longer-term talk therapy all intensify the push to identify most emotional distress as primarily brain-based. Even if this were true, which is unlikely, it does not follow that every brain-based problem has a simple, mechanical, or pharmaceutical cure.

Some authorities focus only on the biological bases of emotional distress, overlooking the critical role of social, political, and interpersonal factors, as well as earlier traumatic experiences. Chemical and other changes in the brain can alter emotions and moods. So if a woman who is distressed has some below- or above-average level of a chemical in her body, it is difficult, even impossible, to know its cause and effect. The interplay between biological and other factors is complex and still not well understood.

It is difficult to do good research about emotional distress because the multitude of factors that might exacerbate or reduce it cannot be experimentally controlled. Scientists still have much to learn about how the brain, or any other bodily organ or system, creates or aggravates emotional anguish.